Identification of abiotic stress miRNA transcription factor binding motifs (TFBMs) in rice.

Plant growth and yield are affected by many abiotic stresses like salinity, drought, cold and heavy metal; these stresses trigger up and down-regulate several genes through various transcription factors (TFs). Transcription factor binding motifs (TFBMs), located in the upstream region of the genes, associate with TFs to regulate the gene expression. Many factors, including the activation of miRNAs, which are encoded by genes having independent transcription units, regulate the gene expression. TFBMs in the regulatory region of miRNA sequences influence the miRNA expression, which in turn influences the expression of other genes in the cell. However, the current level of information available on TFBMs of miRNA involved in abiotic stress related defense pathway(s) is limited and in-depth studies in this direction may lead to a better understanding of their role in expression and regulation of defense responses in plants. In this study, various aspects related to genomic positions of pre-miRNA, prediction of TSS and TATA box positions and identification of known, unique motifs at regulatory regions of all the reported miRNAs of rice associated with different abiotic stresses are discussed. Sixteen motifs were identified in this study, of which nine are known cis-regulatory elements associated with various stresses, two strong motifs, (CGCCGCCG, CGGCGGCG) and five unique motifs which might play a vital role in the regulation of abiotic stresses related miRNA genes. Common motifs shared by miRNAs that are involved in more than one abiotic stresses were also identified. The motifs identified in this study will be a resource for further functional validation.

Different isoforms of starch-synthesizing enzymes controlling amylose and amylopectin content in rice (Oryza sativa L.).

Starch, composed of amylose and amylopectin, greatly influences rice cooking and textural quality, which in turn is controlled by various isoforms of several enzymes. Activity of one or more isoforms of starch-synthesizing enzymes results in various forms of starch structure based on the amylopectin chain length and average external, internal and core chain length distribution and hence results in varying physicochemical and cooking quality. Since the synthesis of starch is highly complex, it is crucial but essential to understand its biosynthetic pathway, starch structure and effects on the physicochemical properties that control eating and cooking quality, and alongside conduct research on gene/QTL mapping for use in marker-assisted selection (MAS) with a view to improve and select cultivars with most desirable range and class of rice starch properties. This article presents the updates on current understanding of the coordination among various enzymes/isoforms towards rice starch synthesis in endosperm and their effect on rice grain physicochemical, cooking and eating qualities. The efforts in identifying regions responsible for these enzymes by mapping the gene/QTLs have provided a glimpse on their association with physicochemical and cooking properties of rice and, hence, improvement is possible by modifying the allelic pattern, resulting in down or nil regulation of a particular enzyme. The clear understanding of the tissue specific coordination between enzyme isoforms and their subsequent effect in controlling eating and cooking properties will enhance the chances to manipulate them for getting desired range of amylose content (AC) and gelatinization temperature (GT) in improved cultivars through combining desired alleles through MAS.

Activity of RBx 11760, a novel biaryl oxazolidinone, against Clostridium difficile.

OBJECTIVES: RBx 11760, a novel oxazolidinone, was investigated for in vitro and in vivo activity against Clostridium difficile. METHODS: The in vitro activity of RBx 11760 and three other agents against 50 diverse C. difficile clinical isolates and other obligate anaerobic bacteria was determined. The effect of RBx 11760 on sporulation and toxin production was determined against different C. difficile isolates. We used a hamster infection model to investigate the efficacy of RBx 11760, vancomycin and metronidazole. The mechanism of action of RBx 11760 against C. difficile ATCC 43255 was determined by macromolecular synthesis inhibition. RESULTS: RBx 11760 MICs were in the range of 0.5-1 mg/L for C. difficile isolates, and it demonstrated concentration-dependent killing of C. difficile ATCC 43255 and C. difficile 6387 up to 2-4× MIC (1-2 mg/L). RBx 11760, at concentrations as low as 0.25-0.5 mg/L, resulted in a significant reduction in de novo toxin production as well as sporulation in different C. difficile isolates. In contrast, vancomycin, metronidazole and linezolid had little or no effect on toxin production and appeared to promote the formation of spores. In the hamster infection model, treatment with RBx 11760 resulted in prolonged survival of animals as compared with vancomycin or metronidazole, which correlated well with the histopathology results. Macromolecular labelling results suggest that RBx 11760 is a potent inhibitor of bacterial protein synthesis. CONCLUSIONS: RBx 11760 showed excellent in vitro and in vivo activity against C. difficile, and it could be a promising novel candidate for future drug development against C. difficile infection.

Activity of a novel series of acylides active against community-acquired respiratory pathogens.

Resistance to macrolides and beta-lactams has increased sharply amongst key respiratory pathogens, leading to major concern. A novel series of acylides was designed to overcome this resistance and was evaluated for in vitro and in vivo activity. This series of acylides was designed starting from clarithromycin by changing the substitution on the desosamine nitrogen, followed by conversion to 3-O-acyl and 11,12-carbamate. Minimum inhibitory concentrations (MICs) of acylides were determined against susceptible as well as macrolide-lincosamide-streptogramin B (MLS(B))--and penicillin-resistant Streptococcus pneumoniae, Streptococcus pyogenes and Moraxella catarrhalis by the agar dilution method. Microbroth MICs for Haemophilus influenzae were determined according to Clinical and Laboratory Standards Institute guidelines. In vivo efficacy was determined by target organ load reduction against S. pneumoniae 3579 (ermB). The bactericidal potential of promising acylides was also determined. MICs of these compounds against S. pneumoniae, S. pyogenes, H. influenzae and M. catarrhalis were in the range of 0.06-2, 0.125-1, 1-16 and 0.015-0.5 microg/mL, respectively, irrespective of their resistance pattern. Mycoplasma pneumoniae and Legionella pneumophila showed MIC ranges of 0.004-0.125 microg/mL and 0.004-0.03 microg/mL, respectively. The acylides also showed better activity against telithromycin-resistant S. pneumoniae strains. Compounds with a 4-furan-2-yl-1H-imidazolyl side chain on the carbamate (RBx 10000296) showed a target organ load reduction of >3 log(10) colony-forming units/mL and concentration-dependent bactericidal potential against S. pneumoniae 994 mefA and H. influenzae strains. This novel and potent series of acylides active against antibiotic-resistant respiratory pathogens should be further investigated.

Allele mining in crops: prospects and potentials.

Enormous sequence information is available in public databases as a result of sequencing of diverse crop genomes. It is important to use this genomic information for the identification and isolation of novel and superior alleles of agronomically important genes from crop gene pools to suitably deploy for the development of improved cultivars. Allele mining is a promising approach to dissect naturally occurring allelic variation at candidate genes controlling key agronomic traits which has potential applications in crop improvement programs. It helps in tracing the evolution of alleles, identification of new haplotypes and development of allele-specific markers for use in marker-assisted selection. Realizing the immense potential of allele mining, concerted allele mining efforts are underway in many international crop research institutes. This review examines the concepts, approaches and applications of allele mining along with the challenges associated while emphasizing the need for more refined 'mining' strategies for accelerating the process of allele discovery and its utilization in molecular breeding.

Scapulothoracic dissociation--A case report.

Scapulothoracic dissociation (SCTD) is a rare clinical entity with fewer than 70 cases reported in English literature. The mechanism of injury is severe rotational force, which causes disruption of the shoulder girdle from the rest of chest wall. Frequently, SCTD produces massive blood loss as it involves major fractures of the upper extremity, disruption of muscle, brachial plexus, and vascular damage. This case report demonstrates classical radiological findings of SCTD with brachial plexus injury but with no associated vascular damage.